[Bug]: iOS text selection stops at the first paragraph of a blockquote

[caiopizzol]

Area

apps/mobile

Steps to reproduce

1. In the iOS app, open a message that has a multi-paragraph blockquote:

   > First quoted paragraph.
   >
   > Second quoted paragraph.

2. Long-press a word in the first quoted paragraph.

3. Drag the selection handle into the second quoted paragraph.

Video:
https://github.com/user-attachments/assets/e29f6ba3-054c-4411-9ccc-0ee93b1ad344

Expected behavior

The selection extends across the quoted paragraphs, as it does for paragraphs that are not quoted.

Actual behavior

The selection stops at the end of the first quoted paragraph. With the > markers removed, the same text can be selected across paragraphs.

Cause

Each paragraph inside a blockquote is rendered in its own native text view, and iOS text selection cannot cross from one text view to another.

• nativeMarkdownDocumentChunks puts consecutive plain blocks in one selectable text view. containsRichBlock marks blockquotes as rich, so a quote is split into its own chunk.
• The blockquote case in NativeMarkdownBlock renders the quote's children one at a time, so each paragraph gets its own NativeMarkdownSelectableText. On iOS, each one is a separate UITextView.
• Blockquotes became separate chunks in fix(mobile): extend blockquotes across wrapped lines #6482, which drew the quote bar as a border so it spans wrapped lines. Before that, quotes stayed in the surrounding text view.

A temporary unit test on main @ d2c9281b8 confirmed the split. A four-paragraph quote becomes its own chunk, and each of its paragraphs renders as a separate text view. Without the quote, the same paragraphs stay in one chunk.

I haven't checked this on the iOS Simulator or on Android. Android uses the same chunking, so it may have the same problem.

Impact

Minor bug or occasional failure

Version or commit

main @ d2c9281b8. Introduced in #6482, first released in v0.0.34.

Environment

T3 Code iOS app on iPhone

Workaround

Use Copy message to copy the whole message, or copy one quoted paragraph at a time.

[juliusmarminge]

Triage

Confirmed on main at d2c9281b8. The selection stops inside the quote, not at the chunk boundary with the surrounding message.

containsRichBlock does send the whole blockquote down the rich path, which is why it is one chunk. The break between quoted paragraphs is the blockquote branch in NativeMarkdownBlock: it renders each child on its own, and a paragraph becomes its own NativeMarkdownSelectableText. On iOS that is a separate UITextView, and selection cannot cross text views. Without the > markers, the same paragraphs stay in one plain chunk and one text view, which is why selection works there.

That rich path should stay. #6482 (shipped in v0.0.34) moved blockquotes there so the bar is a border that spans wrapped lines. Putting the quote back into the parent selectable string would restore the old │ glyph, which only painted the first wrapped line.

The border can stay a parent view. Consecutive plain children inside it (paragraphs, and plain lists) can be one selectable text node. Code, tables, images, and nested quotes still need their own views, same as elsewhere in the message.

Android has used this same tree since #11128 (v0.0.42): each quoted paragraph is its own Text. I have not run it on a device. No existing duplicate. Copy message, or copying one quoted paragraph at a time, is still the workaround.